36:
196:
136:(i.e., a uniform substance that has the same composition throughout the material). The perfect pure chemical will pass all attempts to separate and purify it further. Thirdly, and here we focus on the common chemical definition, it should not contain any trace of any other kind of chemical species. In reality, there are no absolutely 100% pure chemical compounds, as there is always some small amount of
279:
297:, the elements added to the original crystal structure, contain a different number of electrons then the base formula. Semiconductors that are p-doped contains a small amount of elements that have less valence electrons then the other elements in the crystal. N-doping is the opposite and the dopant contains more valence electrons.
156:
to acquire certain properties of a material such as the color in gemstones or conductivity in semiconductors. Impurities may also affect crystallization as they can act as nucleation sites that start crystal growth. Impurities can also play a role in nucleation of other phase transitions in the form of defects.
155:
of a chemical or commercial product. During production, impurities may be purposely or accidentally added to the substance. The removal of unwanted impurities may require the use of separation or purification techniques such as distillation or zone refining. In other cases, impurities might be added
218:
No matter what method is used, it is usually impossible to separate an impurity completely from a material. The reason that it is impossible to remove impurities completely is of thermodynamic nature and is predicted by the second law of thermodynamics. Removing impurities completely means reducing
235:
Occasionally, we may want to include impurities in a material to change its properties. These impurities can be naturally occurring and left unaltered in a material or be intentionally added during synthesis. These types of impurities can show up in our day-to-day lives such as different colors in
215:. This is done by heating the water so it boils and leaves behind the salt. The water is cooled and the gas turns back to a pure liquid. Impurities are usually physically removed from liquids and gases. Removal of sand particles from metal ore is one example with solids.
226:
Impurities in pharmaceuticals and therapeutics are of special concern and the last couple of decades have witnessed a fair number of scandals, from insecure ingredients and incorrect dosage forms to intentionally fortified medications and accidental contaminations.
147:
have been established by various organizations that attempt to define the permitted levels of various impurities in a manufactured product. Strictly speaking, a material's level of purity can only be stated as being more or less pure than some other material.
345:
Impurities play an important role in the nucleation of other phase transitions. For example, the presence of foreign elements may have important effects on the mechanical and magnetic properties of metal alloys. Iron atoms in copper cause the renowned
321:
below its melting point without becoming a solid. This occurs because the liquid has nothing to condense around so the solid cannot form a natural crystalline solid. The solid is eventually formed when
374:
of a new phase is lower at a point defect. In order for the nucleus of a new phase to be stable, it must reach a critical size. This threshold size is often lower at an impurity site.
725:
718:
479:
711:
854:
172:
and leaf pieces in blank white papers. The removal of impurities is usually done chemically. For example, in the manufacturing of
317:
around the impurities and becomes a crystalline solid. If there are no impurities then the liquid is said to be pure and can be
625:
497:
641:
Urwin, Stephanie J.; Levilain, Guillaume; Marziano, Ivan; Merritt, Jeremy M.; Houson, Ian; Ter Horst, Joop H. (2020-08-21).
263:. Pure beryl will appear colorless but this rarely occurs and the presence of trace elements change its color. The green of
888:
289:
is a process where impurities are purposefully added to semiconductors to increase electrical conductivity and improve a
223:. What technicians can do is to increase the purity of a material to as near 100% as possible or economically feasible.
776:
79:
57:
50:
915:
829:
350:
where the conduction electron spins form a magnetic bound state with the impurity atom. Magnetic impurities in
164:
Impurities can become unwanted when they prevent the working nature of the material. Examples include ash and
220:
192:, another purification method, is an economically important method for the purification of semiconductors.
267:
are from impurities such as chromium, vanadium, or iron. A manganese impurity will give a pink gem called
219:
their concentration to zero. This would require an infinite amount of work and energy as predicted by the
239:
An example of when impurities are wanted is shown in gems. These gems have slight impurities that act as
761:
17:
793:
44:
849:
607:
371:
803:
286:
61:
920:
834:
643:"A Structured Approach To Cope with Impurities during Industrial Crystallization Development"
579:
203:
However, some kinds of impurities can be removed by physical means. A mixture of water and
121:
703:
8:
453:
212:
910:
675:
642:
552:
517:
152:
105:
428:
771:
746:
680:
662:
621:
557:
539:
493:
97:
124:
of the material or compound. Firstly, a pure chemical should appear in at least one
766:
756:
670:
654:
613:
547:
529:
485:
367:
339:
327:
310:
272:
884:
351:
331:
268:
181:
144:
195:
143:
The levels of impurities in a material are generally defined in relative terms.
871:
839:
323:
125:
904:
879:
666:
658:
543:
398:
306:
290:
189:
177:
137:
129:
813:
783:
684:
561:
534:
481:
Distillation
Control, Optimization, and Tuning: Fundamentals and Strategies
347:
208:
617:
518:"Chemical Impurities: An Epistemological Riddle with Serious Side Effects"
359:
318:
240:
133:
821:
363:
27:
Substance within a material that differs from its chemical composition
408:
393:
93:
861:
788:
489:
388:
366:. In general impurities are able to serve as initiation points for
236:
gemstones or by doping to tune the conductivity of semiconductors.
185:
516:
Abdin, Ahmad Yaman; Yeboah, Prince; Jacob, Claus (February 2020).
798:
522:
International
Journal of Environmental Research and Public Health
314:
264:
751:
355:
294:
169:
165:
109:
383:
335:
244:
117:
640:
733:
403:
243:
and give the stone its color. An example is the gem family
204:
173:
278:
151:
Impurities are either naturally occurring or added during
113:
358:
defects. Point defects can nucleate reversed domains in
282:
Three gems from the beryl family with different colors.
370:
because the energetic cost of creating a finite-size
211:, with water as the distillate and salt as the solid
902:
515:
132:. Secondly, a pure chemical should prove to be
719:
580:"Gem-Stones and Their Distinctive Characters"
300:
726:
712:
647:Organic Process Research & Development
674:
551:
533:
247:witch has the base chemical formula of Be
80:Learn how and when to remove this message
855:List of medicine contamination incidents
277:
194:
43:This article includes a list of general
734:Combined substance use and adulteration
477:
305:When an impure liquid is cooled to its
14:
903:
159:
707:
511:
509:
128:and can also be characterized by its
889:List of reagent testing color charts
601:
599:
573:
571:
230:
176:, calcium carbonate is added to the
29:
605:
24:
777:List of polysubstance combinations
506:
354:can serve as generation sites for
49:it lacks sufficient corresponding
25:
932:
596:
578:Smith, George Frederick Herbert.
577:
568:
830:Counterfeit illegal drug selling
700:, Aristo-Wilson, Hong Kong, 2004
34:
698:Chemistry – A Modern View
634:
471:
446:
421:
362:and dramatically affect their
271:and iron creates the blue gem
13:
1:
609:Doping in Conjugated Polymers
478:Robbins, Lanny (2011-05-27).
414:
330:occurs, but it forms into an
221:second law of thermodynamics
108:inside a confined amount of
7:
454:"Definition of HOMOGENEOUS"
377:
199:A basic distillation set up
10:
937:
762:Combined drug intoxication
606:Kar, Pradip (2013-08-23).
338:, instead, as there is no
870:
812:
739:
484:. Boca Raton: CRC Press.
309:the liquid, undergoing a
301:Impurities and nucleation
794:Polysubstance dependence
659:10.1021/acs.oprd.0c00166
429:"Definition of IMPURITY"
916:Environmental chemistry
850:Counterfeit medications
458:www.merriam-webster.com
433:www.merriam-webster.com
120:. They differ from the
64:more precise citations.
740:Combined substance use
535:10.3390/ijerph17031030
283:
200:
835:Clandestine chemistry
618:10.1002/9781118816639
612:(1 ed.). Wiley.
281:
198:
207:can be separated by
122:chemical composition
160:Unwanted impurities
106:chemical substances
696:Cheng, E. et al.,
342:in the structure.
284:
201:
898:
897:
772:Polysubstance use
747:Active metabolite
627:978-1-118-57380-8
499:978-0-429-10729-0
368:phase transitions
231:Wanted impurities
98:materials science
90:
89:
82:
16:(Redirected from
928:
767:Drug interaction
757:Combination drug
728:
721:
714:
705:
704:
689:
688:
678:
653:(8): 1443–1456.
638:
632:
631:
603:
594:
593:
591:
590:
575:
566:
565:
555:
537:
513:
504:
503:
475:
469:
468:
466:
465:
450:
444:
443:
441:
440:
425:
340:long-range order
328:glass transition
311:phase transition
85:
78:
74:
71:
65:
60:this article by
51:inline citations
38:
37:
30:
21:
936:
935:
931:
930:
929:
927:
926:
925:
901:
900:
899:
894:
885:Reagent testing
866:
808:
735:
732:
693:
692:
639:
635:
628:
604:
597:
588:
586:
576:
569:
514:
507:
500:
476:
472:
463:
461:
452:
451:
447:
438:
436:
427:
426:
422:
417:
380:
352:superconductors
332:amorphous solid
303:
262:
258:
254:
250:
233:
182:silicon dioxide
162:
86:
75:
69:
66:
56:Please help to
55:
39:
35:
28:
23:
22:
15:
12:
11:
5:
934:
924:
923:
918:
913:
896:
895:
893:
892:
882:
876:
874:
872:Harm reduction
868:
867:
865:
864:
859:
858:
857:
852:
844:
843:
842:
837:
832:
826:Illegal drugs
824:
818:
816:
810:
809:
807:
806:
801:
796:
791:
786:
781:
780:
779:
769:
764:
759:
754:
749:
743:
741:
737:
736:
731:
730:
723:
716:
708:
702:
701:
691:
690:
633:
626:
595:
567:
505:
498:
490:10.1201/b10875
470:
445:
419:
418:
416:
413:
412:
411:
406:
401:
396:
391:
386:
379:
376:
324:dynamic arrest
302:
299:
293:function. The
291:semiconductors
260:
256:
252:
248:
232:
229:
178:blast furnaces
161:
158:
126:chemical phase
88:
87:
42:
40:
33:
26:
9:
6:
4:
3:
2:
933:
922:
919:
917:
914:
912:
909:
908:
906:
890:
886:
883:
881:
880:Drug checking
878:
877:
875:
873:
869:
863:
860:
856:
853:
851:
848:
847:
845:
841:
838:
836:
833:
831:
828:
827:
825:
823:
820:
819:
817:
815:
811:
805:
802:
800:
797:
795:
792:
790:
787:
785:
782:
778:
775:
774:
773:
770:
768:
765:
763:
760:
758:
755:
753:
750:
748:
745:
744:
742:
738:
729:
724:
722:
717:
715:
710:
709:
706:
699:
695:
694:
686:
682:
677:
672:
668:
664:
660:
656:
652:
648:
644:
637:
629:
623:
619:
615:
611:
610:
602:
600:
585:
584:gutenberg.org
581:
574:
572:
563:
559:
554:
549:
545:
541:
536:
531:
527:
523:
519:
512:
510:
501:
495:
491:
487:
483:
482:
474:
459:
455:
449:
434:
430:
424:
420:
410:
407:
405:
402:
400:
399:Semiconductor
397:
395:
392:
390:
387:
385:
382:
381:
375:
373:
369:
365:
361:
357:
353:
349:
343:
341:
337:
333:
329:
325:
320:
316:
312:
308:
307:melting point
298:
296:
292:
288:
280:
276:
274:
270:
266:
246:
242:
237:
228:
224:
222:
216:
214:
210:
206:
197:
193:
191:
190:Zone refining
187:
183:
179:
175:
171:
167:
157:
154:
149:
146:
141:
139:
138:contamination
135:
131:
130:phase diagram
127:
123:
119:
115:
111:
107:
103:
99:
95:
84:
81:
73:
63:
59:
53:
52:
46:
41:
32:
31:
19:
921:Adulteration
814:Adulteration
784:Polypharmacy
697:
650:
646:
636:
608:
587:. Retrieved
583:
525:
521:
480:
473:
462:. Retrieved
460:. 2024-03-10
457:
448:
437:. Retrieved
435:. 2024-03-24
432:
423:
360:ferromagnets
348:Kondo effect
344:
315:crystallizes
304:
285:
241:chromophores
238:
234:
225:
217:
209:distillation
202:
163:
150:
142:
101:
91:
76:
70:January 2021
67:
48:
528:(3): 1030.
319:supercooled
134:homogeneous
62:introducing
905:Categories
846:Medicines
822:Drug fraud
589:2024-04-15
464:2024-03-27
439:2024-04-01
415:References
364:coercivity
273:aquamarine
180:to remove
102:impurities
45:references
18:Impurities
911:Materials
667:1083-6160
544:1661-7827
409:Spin wave
394:Pollution
269:morganite
184:from the
153:synthesis
145:Standards
94:chemistry
862:Impurity
789:Polypill
685:32905065
562:32041209
389:Fineness
378:See also
265:emeralds
186:iron ore
804:Synergy
799:Prodrug
676:7461122
553:7038150
295:dopants
213:residue
58:improve
840:Lacing
752:Codrug
683:
673:
665:
624:
560:
550:
542:
496:
372:domain
356:vortex
287:Doping
170:metals
166:debris
110:liquid
47:, but
384:Dross
336:glass
245:beryl
118:solid
116:, or
681:PMID
663:ISSN
622:ISBN
558:PMID
540:ISSN
494:ISBN
404:Slag
334:– a
255:(SiO
205:salt
174:iron
104:are
96:and
671:PMC
655:doi
614:doi
548:PMC
530:doi
486:doi
326:or
188:.
168:in
114:gas
92:In
907::
679:.
669:.
661:.
651:24
649:.
645:.
620:.
598:^
582:.
570:^
556:.
546:.
538:.
526:17
524:.
520:.
508:^
492:.
456:.
431:.
313:,
275:.
251:Al
140:.
112:,
100:,
891:)
887:(
727:e
720:t
713:v
687:.
657::
630:.
616::
592:.
564:.
532::
502:.
488::
467:.
442:.
261:6
259:)
257:3
253:2
249:3
83:)
77:(
72:)
68:(
54:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.